Chromatographic apparatus for analyzing a rich oil sample

ABSTRACT

An apparatus for heating and vaporizing a rich oil sample, mixing the sample vapors, diluting the vapor sample with a diluent gas, mixing the diluted vapors sample, extracting first and second volumes of a vapor sample, and selectively extracting and passing first and second different groups of hydrocarbons from the respective first and second vapor samples to separate first and second detectors.

United States Patent 1 1 Reinecke CHROMATOGRAPHIC APPARATUS FOR ANALYZING A RICH OIL SAMPLE [75] Inventor: Marvin E. Reinecke, Bartlesville,

Okla.

[73] Assignee: Phillips Petroleum Company, Bartlesville, Okla.

22 Filed: Dec.28, 1970 21 Appl.No.: 101,999

M lMarch 13, 1973 1/1971 Mitacek ..73/23.l X

Primary Examiner-Richard C. Queisser Assistant ExaminerC. E. Snee, III Attorney-Young and Quigg 52 us. Cl ..73/23.i [51] Int. Cl. ..G0ln 31/08 57 ABSTRACT [58] Field ofSearch ..73/23.1,415,422 GC;

23 232 3 232 137 04; 250 4 An apparatus for heating and vaporizing a rich O11 sample, mixing the sample vapors, diluting the vapor [56] References Cit d sample with a diluent gas, mixing the diluted vapors sample, extracting first and second volumes of a vapor UNITED STATES PATENTS sample, and selectively extracting and passing first and 3,567,389 3 1971 Coulteret al. ..73 421 R x Second different groups of hWhOmYbOnSv from the 3,234,779 2/1966 Dawson ..73/23.1 respective first and second vapor samples to separate 2,647,732 8/1953 Jarman.... ....259/4 first and second detectors. 3,263,493 8/1966 Davids0n.... .73/23.1 X 3,520,171 7/1970 Amati et al ..73/23.1 2 Claims, 2 Drawing Figures l [AIR I I n I I I 24 I a I 2 I 2o I U I I I I I I I PATENTEUHARI 3mm FIG.

INVENTOR. M E REIN ECKE ATTORNEYS CHROMATOGRAPHIC APPARATUS FOR ANALYZING A RICH OIL SAMPLE In gas analysis, it is extremely difficult and often impossible to obtain an accurate, representative sample of vapors for analysis from a liquid sample containing a wide range of hydrocarbons having a wide range of boiling points. In addition, it has heretofore been extremely difficult to separate rich oil vapors sample into hydrocarbon groups that could be accurately analyzed. The term rich oil is meant to define a liquid oil containing lighter gases and/or vapors absorbed therein.

This invention therefore provides an apparatus for vaporizing a rich oil sample, adding a dilutinggas to the vapor sample, maintaining the diluted sample in a gaseous phase, thoroughly mixing the diluted hydrocarbons separating the diluted sample into first and second samples and separately passing a different group of hydrocarbons from each first and second sample to analysis.

It is therefore an object of this invention to provide apparatus for preparing vaporous representative samples of a rich oil for analysis and delivering the vaporous samples in a form whereby the-hydrocabrons of the rich oil can be accurately analyzed.

Other aspects, objects, and advantages of the present invention will become apparent from a study of the disclosure, the appended claims, and the drawing.

The drawings are diagrammatic views of the ap paratus of this invention.

FIG. 1 shows the apparatus of this invention and FIG. 2 shows a partial cross-sectional view of a dilution tank of the apparatus of FIG. 1.

Referring to FIG. 1, a conduit 2 passes a pressurized rich oil into a first indirect heater 4 or oven. A pressure regulator 6, such as a controlling valve, for example, is positioned within the conduit 2 in the heater 4 for expanding the rich oil and vaporizing said rich oil as it passes through a coil 8 within the heater 4. The coil 8 is preferably associated with the conduit 2 within the heater 4 for supplying additional heating time and surface to the sample to assure complete vaporization of the rich oil passing therethrough. Inlet and outlet lines l0, 12 are connected to the heater 4 and to a heating fluid source, not shown, for pas sing heating fluid into the heater 4 for maintaining the temperature within the heater at a preselected value sufficient for assuring vaporization of-the sample, for example, about 260 F.

A mixing tank- 18 having a chamber 20 and an inlet 22 and an outlet '24 incommunication with the' chamber 20 is attached at the inlet 22 to the coil 8 for receiving the vaporized sample therefrom and mixing said vapors together.

A dilution means 28, such as the sampling valve described in U.S. Pat. No. 3,387,496 or the like, is connected in communication with the outlet 24 of the mixing tank 18 for receiving the vaporized sample from the mixing tank 18 and mixing a diluting gas with said vaporized sample. The dilution means 28 is connected. via line .14 to a dilution tank 30. The dilution tank 30 has a longitudinal axis, achamber 32, and first and second opposed ends 34,36 andisconnected at the first end 34 to the dilution means 28. for receiving the diluting gas and sample from the dilution means 28 and mix ing said gas and sample therein. The vacuum pump (not shown) is connected via line 16 to the dilution tank 30 for moving the diluting gas and sample from the dilution means 28 into the dilution tank 30 and for removing all of the diluting gas and sample from the dilution means 28 and associated lines for evacuation of the system. A;

Referring to FIG. 2, a conduit 38 directs the diluting gas and sample from the dilution means 28 to the dilution tank 30 and, owing to the configuration of said conduit 38, causes the diluting gas and sample to flow about the longitudinal axis of the dilution tank 30 and mix one with the other. In the preferred embodiment shown in FIG. 2, the conduit 38 enters the chamber 32 of the tank 30 at the first end 34 of said tank 30, extends outwardly to a position adjacent an inner surface 40 of the tank 30 and then a distance of at least about 1/8 of the circumference about the inner surface 40, for example.

First and second sample valves 42,44 are connected in series to the dilution tank 30 in communication with the chamber 32 of the tank 30 for receiving first and second vapor samples of substantially equal volume therefrom. These samples are taken from the dilution tank 30 after thorough mixing of the constituents therein and are each of constituents in common proportions.

First and second columns 45,47 are connected to the respective first and second sample valves 42,44. Each column 45 ,47 contains material for selectively separating a different group of hydrocarbons from the sample and passing the separated group of hydrocarbons to a separate analyzer 54,56 for analysis.

For example,a first column 45 is made up of two sections-a precut section 46 and a measuring section 46. The precut section 46' is, for example, 4 feet long and wit-inch outer diameter. It is packed with, for example, a packing material 50 such as 80-100 mesh Chromosorb P manufactured by Johns-Manville, Box 1960, Trenton, N.J., on which is placed Squalane in an amount equivalent to 20 percent of Chromosorb P. Squalane is produced and sold by Eastman Kodak C0,, Organic Chemicals Dept., Rochester, N.Y. The measuringsection 46 is, for example, 6 feet long and V;- inch outer diameter and is packed with a packing material 51. The packing material 51 is, for example, Porosi] B sold by Waters Associates, Inc., 61 Fountain St., Farmington, Mass. Column 46' is connected to the first sample valve 42 for receiving and passing the first vapor sample therethrough. A second column 47 is, for example, made up of two sections, a precut section 48' and a measuring section 48. The precut section 48' is, for example, a capillary column 10 mils inner diameter, coated inside with DC 200 silicone fluid coating material 52. The precut section 48' is, for example, feet in length. The measuring capillary section 48 is, for example, likewise 10 mils inner diameter, coated with DC 200 silicone fluid coating material 52, and is 300 feet in length. The DC 200 silicone fluid is sold by Dow Corning Corp., Midland, Mich.

The second column 47 is connected to the second sample valve 44 for receiving and passing the second vapor sample therethrough. Each of the columns 46,48 is thereafter attached to separate detectors 54,56 such as, for example, a flame ionization-detector as disclosed in U.S. Pat. No. 3,056,848 for passing vapors from the column to the analyzer for analysis. The first materials 50' and 51 packed in the first column 45 are materials that separate and elute a first group of hydrocarbons of the sample, such as hydrocarbons in the range of C,-C, for example, from the column 46 to the detector 54 and the second material 52 packed in the second column 48 is a material that separates and elutes substantially all of the other hydrocarbons of the sample, such as hydrocarbons in the range of C -C for example, from the column 47 to the detector 56. It should be understood, however, that the,,c0lur'nns 45,47 and their respective'packing and coatingrnaterials 50,51,52 can be different than described above so long as each column 45,47 separates and passes a different group of hydrocarbons to the analyzer and that the summation of all of the hydrocarbon groups separated and passed to the analyzers are equal to substantially the total of the hydrocarbons of the rich oil being analyzed.

In the method of this invention, a pressurized volume of rich oil to be analyzed is passed through the regulator 6, via conduit 2, and the heater 4. As the oil sample passes through the regulator 6, the pressure of the oil is decreased. This pressure drop causes the oil sample to substantially completely vaporize and form a vaporized sample. To assure vaporization of the complete sample, the sample is heated by the heater 4 to a temperature sufficient at the vaporized pressure of the sample.

This vaporization and heating of the sample, owing to the different boiling points of the individual constituents of the sample, causes some separation in the pipe of one component with another. The sample is then passed through the mixing tank 18 wherein the individual vapor constituents are thoroughly mixed thereby causing each unit of vapor to be representative of the original rich oil sample. The mixing tank has been found very critical in forming a representative vapor sample.

The vapor sample is thereafter diluted a preselected amount with a diluting gas, such as air, for example. The dilution is necessary for lowering the dew point of the sample to a value at which condensation is prevented in the analyzing columns 45,47. These analyzing columns 45,47 and associated sampling valves 42,44 can also be maintained within a second indirect heater 58 for operating the columns 45,47 at a preselected temperature sufficient for assuring against gas condensation.

The diluted vapor sample is thereafter further mixed in the dilution tank to cause a representative diluted sample to be formed. Here, again, without providing a dilution mixing tank and causing the vapors to move about the axis of the tank and be mixed together, the diluted samples taken from the tank would not be representative of the sample oil.

The extraction of a representative vapor sample is also assured by withdrawing first and second vapor samples from the dilution tank with first and second serially connected sample valves 42,44.

These first and second samples are thereafter discharged from the sample valves into their respective first and second columns 45,47. At this point it can be seen that the samples entering each column 45,47 are of uniform characteristics and of equal volume. Owing to the different material 50,51,52 packed and coating in each column 46,48 the separated sample constituents eluting or discharging from each column 45,47 to their respective detectors 54,56 are different.

The first column 45, for example, will separate and discharge vapors from a hydrocarbon group in the range of C -C for example, and the second column 47, for example, will separate and discharge a hydrocarbon group in a range greater than C,,. These two streams discharging from their individual columns 45,47 are thereafter separately analyzed thereby providing a more accurate analysis of the rich oil. The separation of hydrocarbon constituents occurs between the portions of the columns 46,46 and 48,48. Movement of the separated constituents through to the separate detectors 54,56 and flushing the precut sections 46,48' can be accomplished by various means known in the art such as, for example, passing flushing fluid through lines 60,62 and into and through their respective columns 45,47.

The vacuum pump (not shown) can be utilized for removing all of the sample and carrier gas from the dilution means 28, dilution tank 30, and associated conduits for clearing the apparatus for another cycle. During this evacuation, valves A and C are closed,

valve B is open, and the vacuum pump is actuated.

After the system is evacuated, the dilution tank can be charged with a preselected volume of sample from the sample loop or dilution means 28 and diluting gun at a fixed pressure of, for example, 35 paig. liy this procedure, fixed amounts of sample gas and diluting gas charge the diluting tank during each cycle which permits more accurate, repeatable analysis to be made. During charging of the diluting tank, valves B and C are closed and valve A is opened for a time sufficient to admit the gases into the diluting tank.

lt has also been found necessary to heat the sample upon expansion and during constituent separation in order to assure complete vaporization of the sample and to maintain the gases in the gaseous condition.

The following is an example of the process of this invention:

EX AM PLE Rich Oil Constituents Component Mol percent Weight percent Nitrogen 0.09 0.04 Methane 16.60 4.50 Ethane 16.87 8.58 Carbon Dioxide 0.14 0.10 Propane 23.58 17.58 lsobutane 3.19 3.14 n-Butane 7.55 7.42 lsopentane 1.78 2. l 8 n-Pentane 1.46 1.79 neo-Hexane 0.02 0.03 Cyclopentane 0.05 0.06 2,3-Dimethylbutane 0.03 0.04 2-Methylpentane 0.32 0.47 S-Methylpentane 0.17 0.25 n-Hexane 0.39 0.57 2,2-Dimethylpentane 0.04 0.06 Methylcyclopentane 0.20 0.29 2,4-Dimethylpentane 0.01 0.02 Benzene 0.08 0.10 2,2,3-Trimethylbutane 0.01 0.01 3,3-Dimethylpentane 0.01 0.02 Cyclohexane 0.41 0.58 Z-Methylhexane 0.24 0.41 2,3-Dimethylpentane 0.03 0.05 3-Methylhexane 0.38 0.64 n-Heptane 0.90 1.52 Dimethylcyclopentanes 0.47 0.78 Methylcyclohexane 2.14 3.55 Toluene 0.82 1.28 n-Octane 3.36 6.51

Trimethylcyclopentanes 0.48 0.91 Ethylcyclohexane 1.34 2.53 Dimethylcyclohexanes 3.48 6.64 C Paraffin Naphthenes 3.10 6.01 Ethylbenzene 0.52 0.91 para-Xylene 0.63 1.13 meta-Xylene 1.84 3 .30 ortho-Xylene 0.55 0.99 n-Nonane 0.78 1.69 G Paraffin Naphthenes 4.70 10.43 C Paraffin Naphthenes 0.80 1.92 C C Benzenes 0.37 0.75 C s 0.07 0.18 C s 0.01 0.03 C s 0.01 0.01

Pressure of the oil 510-525 psi.

Pressure drop through the regulator 500 psi.

Temperature of first oven 260F.

Temperature of second oven 130F.

Approximate mixing time in mixing tank seconds Volume of air added 300 cc (approx.) (3 atmospheres pressure).

Approximate mixing time in dilution tank 1 minute.

Volume of each sample delivered to each column 300 microliters Separating material of the first column 46' Squalane on Chromosorb P 46 Porosil B Separating material in second column 48' DC 200 silicone fluid 48 DC 200 silicone fluid Hydrocarbon groups eluting and passing from the first column to the detector C,C Hydrocarbon groups separated and passed from the second column to the detector Greater than C By the utilization of the apparatus of this invention, complicated and more accurate hydrocarbon analysis can be made in a reduced time.

Other modifications and alterations of this invention will become apparent to those skilled in the art from the foregoing discussion, example, and accompanying drawing, and it should be understood that this invention is not to be undulylimited thereto.

What is claimed is: 1. An apparatus for preparing a rich oil sample for analysis, comprising:

heating means for heating the sample to a preselected temperature;

a pressure regulator within the heating 2 means for reducing the pressure of the sample and vaporizing the sample;

conduit means for passing the sample to a hereafter mixing tank;

a mixing tank having a chamber and inlet and outlets in communication with the chamber and being attached to the conduit means at the inlet of said mixing tank for receiving the vaporized sample and mixing said sample therein;

dilution means connected to the outlet of the mixing tank for receiving vapors therefrom and adding a diluting gas thereto;

a dilution tank having a longitudinal axis, a chamber,

and first and second op ose d ends; means connected to the ilution means and the first end of the dilution tank for delivering the diluted sample vapors from the dilution means into the chamber of the dilution tank and causing the vapors to move about the longitudinal axis of the dilution tank;

first and second sample valves serially connected to the second end of the dilution tank in communication with the chamber of said tank for receiving first and second samples therefrom;

a first column connected to the first sample valve for receiving the first vapor sample;

means within the first column for separating a firs group of hydrocarbons from the vapor sample and passing said first hydrocarbon group therefrom;

a second column being connected to the second sample valve for receiving the second vapor sample; and

means within the second column for separating a different second group of hydrocarbons from the vapor sample and passing said second hydrocarbon group therefrom 2. An apparatus, as set forth in claim 1, wherein the first and second columns are each capillary columns. 

1. An apparatus for preparing a rich oil sample for analysis, comprising: heating means for heating the sample to a preselected temperature; a pressure regulator within the heating zone for reducing the pressure of the sample and vaporizing the sample; conduit means for passing the sample to a hereafter mixing tank; a mixing tank having a chamber and inlet and outlets in communication with the chamber and being attached to the conduit means at the inlet of said mixing tank for receiving the vaporized sample and mixing said sample therein; dilution means connected to the outlet of the mixing tank for receiving vapors therefrom and adding a diluting gas thereto; a dilution tank having a longitudinal axis, a chamber, and first and second opposed ends; means connected to the dilution means and the first end of the dilution tank for delivering the diluted sample vapors from the dilution means into the chamber of the dilution tank and causing the vapors to move about the longitudinal axis of the dilution tank; first and second sample valves serially connected to the second end of the dilution tank in communication with the chamber of said tank for receiving first and second samples therefrom; a first column connected to the first sample valve for receiving the first vapor sample; means within the first column for separating a first group of hydrocarbons from the vapor sample and passing said first hydrocarbon group therefrom; a second column being connected to the second sample valve for receiving the second vapor sample; and means within the second column for separating a different second group of hydrocarbons from the vapor sample and passing said second hydrocarbon group therefrom 